Magnesium-based hydrogen storage materials, with their high hydrogen storage capacity and favorable cost-effectiveness, are promising candidates for addressing the challenges of hydrogen energy storage and transportation. However, their advantages are significantly hindered by high reaction temperatures and sluggish diffusion behavior in the medium-temperature range. To address the issue of sluggish dehydrogenation kinetics, a method for synergistically optimizing the de-/absorption kinetic performance by simultaneously doping with Mg₂Ni and Sc-containing compounds is proposed. By leveraging differences in formation enthalpy, the synthesized material comprises Mg₂Ni, Ni₂Sc, and Mg phases, with the formation of Ni₂Sc inducing microstructural modifications. The formation of Ni₂Sc reduces the Ni concentration in the melt, causing the primary phase in the alloy to shift from Mg₂Ni to Mg. The Mg₈₅Ni₁₄Sc₁ alloy exhibits a hydrogen absorption capacity of 3.6 wt% at 100 ℃ within 105 min, and the hydrogen desorption rate is significantly accelerated. The Mg₂Ni phase is uniformly dispersed within the hydrogen storage particles, while the Ni-Sc compounds are distributed near the particle surfaces. Theoretical calculations indicate that H atoms have lower diffusion energy barriers in Ni₂Sc and Mg₂Ni, with values of 1.60 eV and 1.47 eV, respectively. This arrangement synergistically enhances hydrogen molecule dissociation and atomic hydrogen recombination, resulting in accelerated reaction kinetics. The cooperative effect of these two catalytic phases effectively lowers the endothermic peak temperature of MgH₂ during dehydrogenation by reducing the concentration of H atoms.

The hydrogen de-/absorption properties of high-capacity Mg-based hydrogen storage alloys are hard to improve due to coarse α-Mg grains and catalytic element segregation. In this study, rapid solidification is introduced to Mg₉₇Ni_3-xY_x (x = 0, 0.25, 0.5, 1, at %) alloys, aiming to improve hydrogenation capacity and de-/hydrogenation kinetic jointly. The results indicate that homogeneous and refined microstructure is formed in rapid-solidified fibers, and NiY₃ and Mg₂Ni phases are generated in heat-treated fibers. Hydrogen absorption properties are improved as Y content is increased to 0.5 at %. The in situ generated YH₃ phases produce a “synergistic effect” on MgH₂ desorption and further reduce overall dehydrogenation temperature. Due to the homogeneous and refined microstructure and the ultrafine dispersed YH₂/YH₃ phases introduced by moderate Y doped, the fiber alloy can absorb more hydrogen in stage 1 and improve the hydrogenation capacity and hydrogenation rate.

For the sake of improving the mechanical properties and corrosion resistance of biodegradable Mg alloy synergistically, various content of element V (0, 0.05, 0.10, 0.15, 0.20 wt.%) are introduced into an Mg-Zn-Y alloy with long-period stacking ordered (LPSO) structure, and the effects of V on its microstructure, mechanical properties and corrosion resistance are investigated systematically. The results indicate that the grains are effectively refined by V addition, and the primary α-Mg in Mg-Zn-Y-V0.1 alloy is most significantly refined, with grain size being decreased by 62%. The amount of 18R LPSO structure is increased owing to the V addition. The growth mode of the second phase (W-phase and 18R LPSO structure) is transformed to divorced growth pattern, which ascribes to the thermodynamic drive force of V to promote the nucleation of LPSO phase. Thus, 18R LPSO structure presents a continuous distribution. Due to grains refinement and modification of second phase, the tensile strength and strain of alloys are both enhanced effectively. Especially, the ultimate tensile strength and the elongation of V0.1 alloy are 254 MPa and 15.26%, which are 41% and 61% higher than those of V-free alloy, respectively. Owing to the continuously distributed 18R LPSO structure with refined grains and stable product film, the weight loss and hydrogen evolution corrosion rates of V0.1 alloy are 7.1 and 6.2 mmy⁻¹, respectively, which are 42.6% and 45.4% lower than those of V-free alloy.